Mystery Bird: Indigo bunting, Passerina cyanea

An immature male indigo bunting, Passerina cyanea (formerly; Tanagra cyanea ), photographed at Heritage Community Park , Blacksburg, Virginia, USA. Image: Audrey DeRose-Wilson, 2 October 2010 (look at this bird with binoculars ). Nikon D80, 70-300mm, f/5.6, 1/400, iso: 160 Question: This neotropical migrant's blue plumage is not based on pigments at all. Instead, it uses another strategy to create blue feathers. Can you tell me about that? Response: Birds do not have blue pigments so they do not have blue pigment-based plumage. Instead, they create blue feathers using a few physics tricks where their feather structure manipulates light waves .